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authorPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-10-04 14:43:41 +0400
committerPaul E. McKenney <paulmck@linux.vnet.ibm.com>2014-11-13 21:35:39 +0300
commitb6331ae8afe4118884c4b6e14a213758d88422b2 (patch)
treed8e91863e7ddd26f8bc98f066dc8ea0ab24c7501 /include/linux/rcupdate.h
parent1a6c9b2675460718f819def9a272cca35575eeb7 (diff)
downloadlinux-b6331ae8afe4118884c4b6e14a213758d88422b2.tar.xz
rcu: Optimize cond_resched_rcu_qs()
The current implementation of cond_resched_rcu_qs() can invoke rcu_note_voluntary_context_switch() twice in the should_resched() case, once via the call to __schedule() and once directly. However, as noted by Joe Lawrence in a patch to the team subsystem, cond_resched() returns an indication as to whether or not the call to __schedule() actually happened. This commit therefore changes cond_resched_rcu_qs() so as to invoke rcu_note_voluntary_context_switch() only when __schedule() was not called. Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Diffstat (limited to 'include/linux/rcupdate.h')
-rw-r--r--include/linux/rcupdate.h4
1 files changed, 2 insertions, 2 deletions
diff --git a/include/linux/rcupdate.h b/include/linux/rcupdate.h
index a033d8b55773..36ea3ba5c516 100644
--- a/include/linux/rcupdate.h
+++ b/include/linux/rcupdate.h
@@ -348,8 +348,8 @@ extern struct srcu_struct tasks_rcu_exit_srcu;
*/
#define cond_resched_rcu_qs() \
do { \
- rcu_note_voluntary_context_switch(current); \
- cond_resched(); \
+ if (!cond_resched()) \
+ rcu_note_voluntary_context_switch(current); \
} while (0)
#if defined(CONFIG_DEBUG_LOCK_ALLOC) || defined(CONFIG_RCU_TRACE) || defined(CONFIG_SMP)